LS 3 Groups of organisms show evidence of change over time (structures, behaviors, and biochemistry).
National Standards:
Science as Inquiry - Content Standard A: As a result of activities in grades 9-12, all students should develop
Understandings about scientific inquiry
Context of Lesson:
After having introduced the geologic time scale and identifying the origin of life as a major event along the timeline, this lesson introduces how life began. Students first take a quiz on the geologic time scale before the concept of spontaneous generation is introduced. Students will be given examples of how people in the 4th century BC came to conclusions through untested observations, and then asked to identify the importance of scientific investigations. We will then look at the experiments of Francesco Redi and Louis Pasteur, while completing note outlines to guide understanding that these experiments disprove spontaneous generation, and lead to the theory of biogenesis. The concept of primordial soup will be introduced and a demonstration to understand Miller and Urey’s experiment will be given. Students will complete an end of class check-in to formatively assess their understanding of the lesson.
Opportunities to Learn:
Depth of Knowledge
Webbs Level 1 (Recall & Reproduction) - Recall or recognize a fact, term, definition, simple procedure (such as one step), or property; Perform a routine procedure, such as measuring length.
Webb's Level 2 (Skills & Concepts) - Interpret information from a simple graph
Webb's Level 3 (Strategic Thinking) - Explain thinking (beyond a simple explanation or using only a word or two to respond).
Prerequisite Knowledge
Experiments are guided by concepts and are performed to test ideas.
An understanding of the geologic timescale and the point where life originated on Earth.
Using data to develop scientific conclusions and explanations.
Plans for Differentiating Instruction
All students are provided with a guided outline for notes to encourage questions and explanations about the underlying science.
Accommodations and modifications
Guided outline provided for all students to help with note-taking.
Allow students to complete the end of class check-in verbally to me opposed to writing out their answers.
Environmental factors
The classroom is arranged in three rows with four tables in each row. Each table has two or three students sitting at it.
Students will turn to face away from each while taking the quiz to reduce the number of wandering eyes.
Whole class opening, guided notes, discussions, and closing.
After the lesson, students will be able to:
1. Explain experiments that disprove the early idea of spontaneous generation (artifact = notes outline)
2. Define spontaneous generation and biogenesis, and compare the two (artifact = notes outline, end of class check-in)
3. Explain what primordial soup is and how Miller and Urey tested this theory (artifact = end of class check-in)
Instruction:
Opening:
1. The warm-up is on the board for students to complete as they enter the class – “Write out the pneumonic you will use to help you do well on the quiz.”
2. Students take the quiz on the geologic time scale – identifying the Periods, Eras, and some major events.
3. After the quiz: “When did life begin on Earth?" (they should know because it was on their quiz!). "How did life actually come to be? Who wants to offer an idea?" (There will probably be a great variety of answers, and/or a lot of 'I don't knows').
4. "We had some good ideas, some of you were close, some were way off, and some of you had no opinion at all," or "(Student) suggests that (student's idea). Who else thinks this is true...Who doesn't agree?" "Well, let's see what we can find out about the origination of life on Earth..."
Engagement:
Part 1: Discussion
1. “For centuries, people based their beliefs on their interpretations of what they saw going on in the world around them and came to conclusions based on these observations. What is so wrong with going about making conclusions this way? Is it scientific?” (Students should recall the information they know about the scientific method and ways to go about making and testing a good scientific experiment.)
“If we are talking about how life originated on Earth, do you think we need to have scientific evidence to support these conclusions?” (Yes!)
2. Present to students some examples of what people believed in the 4th century BC, and for centuries beyond, based on observations that were made. “From about the 4th century BC and continuing on for centuries, people believed that simple organisms could come into being by spontaneous generation.
Observation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times.
Conclusion: It was perfectly obvious to people back then that muddy soil gave rise to the frogs.
Observation: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around.
Conclusion: It was obvious to them that the mice came from the moldy grain.
Observation: Since there were no refrigerators, the mandatory, daily trip to the butcher shop, especially in summer, meant battling the flies around the carcasses. Typically, carcasses were “hung by their heels,” and customers selected which chunk the butcher would carve off for them.
Conclusion: Obviously, the rotting meat that had been hanging in the sun all day was the source of the flies.
4. “Based on the scenarios just presented, can anyone make an educated guess as to what spontaneous generation is?” After students share their ideas, present the definition (The idea that non-living objects can give rise to living organisms) and have them write it down in their notebooks. Go over the examples so students understand the concept (Frogs arise from muddy soil, mice arise from moldy grain, and flies arise from rotting meat.)
Part 2: Discussion with guided notes
1. Pass out note outline for The Early Ideas. Refer students to page 380-381 of their text. Have a discussion with the students on the two experiments (Redi and Pasteur) that disprove spontaneous generation.
2. Prompt student participation in discussion by asking them questions about the scientific method and how these experiments are more valid than the conclusions made through untested observations.
3. Students will complete the outline throughout the discussion. Questions on the outline will encourage students to ask questions about the experiments and foster discussion.
4. The last question on the note sheet leads into biogenesis, so use this to lead into the primordial demonstration.
Part 3: Primordial soup demonstration/discussion
1. Present the class with a can of Primordial soup (can label found here) and read the ingredients and directions on how to make. Tell students that Primordial soup is a nickname for Earth’s ancient, abiotic oceans, meant to suggest the watery mix of chemicals and sediments in which life somehow began.
2. Ask students what they think about this idea of creating life from Primordial soup. Is there a way to test this hypothesis? Students should provide ideas about how a scientific investigation should be done, although they probably will not know how to exactly go about testing this hypothesis unless they have heard about the theory before. Let students know that no one has yet proven scientifically how life began on earth, but scientists such as Stanley Miller and Harold Urey have done experiments to see if life could actually begin from this Primordial soup.
3. Explain the process of how Miller and Urey tested this hypothesis while doing the following demonstration.
“The energy from the sun, lightning and earth’s earth triggered chemical reactions to produce small organic molecules from the substances in the earth’s atmosphere. These molecules were probably washed into the ocean by rain, forming what is called the primordial soup.” Pour different colored beads to represent the different components (water vapor, ammonia, methane, hydrogen gases etc) in a glass jar and flick a flashlight on and off to represent the lighting/electricity.
“Miller and Urey tested this hypothesis by simulating the conditions of the early earth and sent an electric current through the mixture to simulate lighting. They cooled the mixture of gases, produced a liquid that simulated rain, and collected the liquid in a flask.” Use a diagram (found here) on an overhead projector to help explain the experimental set-up and different steps of the experiment. “When Miller and Urey analyzed the chemicals in the flask a week later, what do you think they found? Indeed, they found several amino acids, sugars and other small organic molecules. You should remember from genetics that amino acids are the building blocks of life, which are definitely important in creating life on earth.”
4. “We’re going to put this soup aside for today, but we will come back to it next class to talk about how complex organic compounds formed, which led to protocells (or pre-cells) and then the formation of first true cells.”
Closure:
1. "So, did we answer what we set out to answer today?"
2. "I would like you to think about this question and what we talked about today to answer these questions..."
3. Have students complete an end of class check-in with the following questions:
What is the difference between spontaneous generation and biogenesis?
Briefly explain either Pausteur’s or Redi’s experiment and how the results of their experiment disproved spontaneous generation.
List the three main components needed to make primordial soup. You do not need to list the specific gases. (Answer: Earth’s early atmosphere, electricity/lightning, and the ocean)
How do we know Miller and Urey’s experiment supported the primordial soup hypothesis?
Is your idea from the beginning of class about how life originated still the same? Briefly explain.
4. Collect students’ answers as they leave class. Review the answers and identify any misconceptions still held or misunderstandings for the day’s lesson. Address at the beginning of next class.
Assessment:
1. Quiz on the geologic timeline.
2. Formative assessment of student answers during discussion of experiments by Redi and Pasteur.
3. Completed guided notes handout.
4. Formative assessment of students’ answers to end of class check-in.
Lesson Title:
The Origin of Life (90 minutes)State Standards: GLEs/GSEs
LS 3 Groups of organisms show evidence of change over time (structures, behaviors, and biochemistry).National Standards:
Science as Inquiry - Content Standard A: As a result of activities in grades 9-12, all students should developContext of Lesson:
After having introduced the geologic time scale and identifying the origin of life as a major event along the timeline, this lesson introduces how life began. Students first take a quiz on the geologic time scale before the concept of spontaneous generation is introduced. Students will be given examples of how people in the 4th century BC came to conclusions through untested observations, and then asked to identify the importance of scientific investigations. We will then look at the experiments of Francesco Redi and Louis Pasteur, while completing note outlines to guide understanding that these experiments disprove spontaneous generation, and lead to the theory of biogenesis. The concept of primordial soup will be introduced and a demonstration to understand Miller and Urey’s experiment will be given. Students will complete an end of class check-in to formatively assess their understanding of the lesson.Opportunities to Learn:
Depth of Knowledge
Prerequisite Knowledge
Plans for Differentiating Instruction
Accommodations and modifications
Environmental factors
Materials
Objectives:
After the lesson, students will be able to:1. Explain experiments that disprove the early idea of spontaneous generation (artifact = notes outline)
2. Define spontaneous generation and biogenesis, and compare the two (artifact = notes outline, end of class check-in)
3. Explain what primordial soup is and how Miller and Urey tested this theory (artifact = end of class check-in)
Instruction:
Opening:
1. The warm-up is on the board for students to complete as they enter the class – “Write out the pneumonic you will use to help you do well on the quiz.”2. Students take the quiz on the geologic time scale – identifying the Periods, Eras, and some major events.
3. After the quiz: “When did life begin on Earth?" (they should know because it was on their quiz!). "How did life actually come to be? Who wants to offer an idea?" (There will probably be a great variety of answers, and/or a lot of 'I don't knows').
4. "We had some good ideas, some of you were close, some were way off, and some of you had no opinion at all," or "(Student) suggests that (student's idea). Who else thinks this is true...Who doesn't agree?" "Well, let's see what we can find out about the origination of life on Earth..."
Engagement:
Part 1: Discussion1. “For centuries, people based their beliefs on their interpretations of what they saw going on in the world around them and came to conclusions based on these observations. What is so wrong with going about making conclusions this way? Is it scientific?” (Students should recall the information they know about the scientific method and ways to go about making and testing a good scientific experiment.)
“If we are talking about how life originated on Earth, do you think we need to have scientific evidence to support these conclusions?” (Yes!)
2. Present to students some examples of what people believed in the 4th century BC, and for centuries beyond, based on observations that were made. “From about the 4th century BC and continuing on for centuries, people believed that simple organisms could come into being by spontaneous generation.
- Observation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times.
Conclusion: It was perfectly obvious to people back then that muddy soil gave rise to the frogs.- Observation: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around.
Conclusion: It was obvious to them that the mice came from the moldy grain.- Observation: Since there were no refrigerators, the mandatory, daily trip to the butcher shop, especially in summer, meant battling the flies around the carcasses. Typically, carcasses were “hung by their heels,” and customers selected which chunk the butcher would carve off for them.
Conclusion: Obviously, the rotting meat that had been hanging in the sun all day was the source of the flies.4. “Based on the scenarios just presented, can anyone make an educated guess as to what spontaneous generation is?” After students share their ideas, present the definition (The idea that non-living objects can give rise to living organisms) and have them write it down in their notebooks. Go over the examples so students understand the concept (Frogs arise from muddy soil, mice arise from moldy grain, and flies arise from rotting meat.)
Part 2: Discussion with guided notes
1. Pass out note outline for The Early Ideas. Refer students to page 380-381 of their text. Have a discussion with the students on the two experiments (Redi and Pasteur) that disprove spontaneous generation.
2. Prompt student participation in discussion by asking them questions about the scientific method and how these experiments are more valid than the conclusions made through untested observations.
3. Students will complete the outline throughout the discussion. Questions on the outline will encourage students to ask questions about the experiments and foster discussion.
4. The last question on the note sheet leads into biogenesis, so use this to lead into the primordial demonstration.
Part 3: Primordial soup demonstration/discussion
1. Present the class with a can of Primordial soup (can label found here) and read the ingredients and directions on how to make. Tell students that Primordial soup is a nickname for Earth’s ancient, abiotic oceans, meant to suggest the watery mix of chemicals and sediments in which life somehow began.
2. Ask students what they think about this idea of creating life from Primordial soup. Is there a way to test this hypothesis? Students should provide ideas about how a scientific investigation should be done, although they probably will not know how to exactly go about testing this hypothesis unless they have heard about the theory before. Let students know that no one has yet proven scientifically how life began on earth, but scientists such as Stanley Miller and Harold Urey have done experiments to see if life could actually begin from this Primordial soup.
3. Explain the process of how Miller and Urey tested this hypothesis while doing the following demonstration.
- “The energy from the sun, lightning and earth’s earth triggered chemical reactions to produce small organic molecules from the substances in the earth’s atmosphere. These molecules were probably washed into the ocean by rain, forming what is called the primordial soup.” Pour different colored beads to represent the different components (water vapor, ammonia, methane, hydrogen gases etc) in a glass jar and flick a flashlight on and off to represent the lighting/electricity.
- “Miller and Urey tested this hypothesis by simulating the conditions of the early earth and sent an electric current through the mixture to simulate lighting. They cooled the mixture of gases, produced a liquid that simulated rain, and collected the liquid in a flask.” Use a diagram (found here) on an overhead projector to help explain the experimental set-up and different steps of the experiment. “When Miller and Urey analyzed the chemicals in the flask a week later, what do you think they found? Indeed, they found several amino acids, sugars and other small organic molecules. You should remember from genetics that amino acids are the building blocks of life, which are definitely important in creating life on earth.”
4. “We’re going to put this soup aside for today, but we will come back to it next class to talk about how complex organic compounds formed, which led to protocells (or pre-cells) and then the formation of first true cells.”Closure:
1. "So, did we answer what we set out to answer today?"2. "I would like you to think about this question and what we talked about today to answer these questions..."
3. Have students complete an end of class check-in with the following questions:
- What is the difference between spontaneous generation and biogenesis?
- Briefly explain either Pausteur’s or Redi’s experiment and how the results of their experiment disproved spontaneous generation.
- List the three main components needed to make primordial soup. You do not need to list the specific gases. (Answer: Earth’s early atmosphere, electricity/lightning, and the ocean)
- How do we know Miller and Urey’s experiment supported the primordial soup hypothesis?
- Is your idea from the beginning of class about how life originated still the same? Briefly explain.
4. Collect students’ answers as they leave class. Review the answers and identify any misconceptions still held or misunderstandings for the day’s lesson. Address at the beginning of next class.Assessment:
1. Quiz on the geologic timeline.2. Formative assessment of student answers during discussion of experiments by Redi and Pasteur.
3. Completed guided notes handout.
4. Formative assessment of students’ answers to end of class check-in.
Reflections (only done after lesson is enacted)
Student Work Sample 1 – Approaching Proficiency:
Student Work Sample 2 – Proficient:
Student Work Sample 3 – Exceeds Proficiency:
Home